It has been reported in both Bukhari and Muslim from Ibn Abbas (Allah be pleased with him), that, "When the Messenger of Allah (blessings and peace be upon him) reached Medina, he found the Jews fasting the Day of `Ashura', so he asked them, 'What is this day you are fasting?' They said, 'This is a tremendous day. Allah saved Musa and his people on this day and drowned Pharaoh and his people. Musa fasted it out of thanks, so we fast it too.' The Messenger of Allah (blessings and peace be upon him) said, 'And we are more deserving of Musa than you are.' So he fasted this day, and ordered that it be fasted."